RE: [ATM] Which stroke ?

["Jerry" <wa4guu@verizon.net>]

-----Original Message-----
From: Jim Burrows


It's generally easier to push this surface toward that parabola, which 
suggests Texereau's parabolizing stoke A II on p. 97, that deepens the 
center.  Really short spells between testing - it's easier to mess up 
rather than improving things when you're so close.

         -- Jim Burrows
<<<<<<<<<<<<


For a mirror on top approach I would think more like A III on page 97 But
not quite as wide a W as the illustration. I think A II will continue the
over correction in the center. 
Now of course the over correction is really a small area, mostly zone 1 and
then just very very slightly zone 2. Zone 1 looks deep but it is not deeper
than the parabola if you were looking at zone 4 as being on the desired
parabola.

I think the hole can really be ignored right now except to just not make it
deeper. The way to keep it from getting deeper is to quit doing what put it
there. It is my guess that what Eric has now is the result of the "normal
parabolization" shown in A I. To my way of thinking the left and right
extent of the W in the illustrations is exaggerated. Going that far left and
right is ok and probably recommended when you have developed the technique
of supporting somewhat the overhanging side of the mirror as you get far out
left and right. The pressure rises to extreme on the center of the mirror
punching the kind of hole Eric has.  Narrowing the W and/or more strokes in
the middle half of the W would help the outer zones catch up with the center
zones and probably rub that hole out by the time the outer ones are close to
100%.

I hope Eric has time to try all of the suggestions. I want to know how all
of them work. I might be making a mirror soon.

Jerry


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